Abstract: A method of detecting the presence and position of radio isotope material in a sample is described comprising the steps of: exposing the sample to a phosphor, repetitively imaging the phosphor onto an image intensified CCD camera, scanning the camera CCD array and interrogating the charge pattern thereon following each exposure, performing measurements on the data signals obtained thereby to identify clusters of data values from adjacent regions of the array caused by light emitted by the image intensifier onto those regions and comparing the measurements with threshold values and parameter values so as to distinguish clusters resulting from light emitted as a result of radioactive decay events energizing the phosphor, from other light producing events, computing the centroid of each cluster of data values identified as a radioactive decay event with reference to the camera array and storing the centroid coordinates in a memory together with the centroid coordinates of any other radioactive decay produced clu

Abstract: A method and apparatus for detecting the mean atomic number of a mass of material, for example freight in a vehicle comprises: subjecting the mass to X-rays and determining the mean number N.sub.A passing therethrough; subjecting the mass to higher energy X-rays and determining the new mean number N.sub.B ; and determining the mean atomic number of the mass from look-up tables against the computed ratio N.sub.A /N.sub.B. The mass, such as a railway wagon, may be scanned by two linear accelerators arranged perpendicular to each other, detector arrays being disposed respectively opposite the accelerators, so that a three dimensional image can be built up of the mass.

Abstract: Apparatus as described by which very low light levels emitted typically by very small regions such as individual cells in cultured monolayers, can be more readily detected by a detector such as a CCD detector or image intensifier. The light capturing aid is a fibre optic face plate located between the light emitting material and the detector, but not in contact with the light emitting material. Where the latter is contained on a surface such as a petri dish, the face plate is positioned between the dish and the detector with at least an air gap between the face plate and the detector.